Convert synchronous methods to async methods

promisify.ts

type PromisifyMethods<T> = {
  [K in keyof T]: T[K] extends AnyFunction ? (...parameters: Parameters<T[K]>) => Promise<ReturnType<T[K]>> : T[K];
};

type AsynchronousStorage = PromisifyMethods<Storage>;

export function promisify(storage: Storage): AsynchronousStorage {
  return new Proxy(storage, {
    get(target, name: string) {
      if (typeof target[name] === 'function') {
        return async function (...args: unknown[]) {
          return Reflect.apply(target[name], storage, args);
        };
      }

      return Reflect.get(target, name, target);
    },
  }) as unknown as AsynchronousStorage;
}